Undegraded chromogranin A is present in serum and enters the endocytotic lysosomal pathway in kidney

Mental health and periodontal and peri-implant diseases

Mental health disorders, particularly depression and anxiety, affect a significant number of the global population. Several pathophysiological pathways for these disorders have been identified, including the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and the immune system. In addition, life events, environmental factors, and lifestyle affect the onset, progression, and recurrence of mental health disorders. These may all overlap with periodontal and/or peri-implant disease. Mental health disorders are associated with more severe periodontal disease and, in some cases, poorer healing outcomes to nonsurgical periodontal therapy. They can result in behavior modification, such as poor oral hygiene practices, tobacco smoking, and alcohol abuse, which are also risk factors for periodontal disease and, therefore, may have a contributory effect. Stress has immunomodulatory effects regulating immune cell numbers and function, as well as proinflammatory cytokine production. Stress markers such as cortisol and catecholamines may modulate periodontal bacterial growth and the expression of virulence factors. Stress and some mental health disorders are accompanied by a low-grade chronic inflammation that may be involved in their relationship with periodontal disease and vice versa. Although the gut microbiome interacting with the central nervous system (gut-brain axis) is thought to play a significant role in mental illness, less is understood about the role of the oral microbiome. The evidence for mental health disorders on implant outcomes is lacking, but may mainly be through behaviourial changes. Through lack of compliance withoral hygiene and maintenance visits, peri-implant health can be affected. Increased smoking and risk of periodontal disease may also affect implant outcomes. Selective serotonin reuptake inhibitors have been linked with higher implant failure. They have an anabolic effect on bone, reducing turnover, which could account for the increased loss.

Co-storage and secretion of growth hormone and secretoneurin in retinal ganglion cells

It is well established that growth hormone (GH) and granins are co-stored and co-secreted from pituitary somatotrophs. In this work we demonstrate for the first time that GH- and secretoneurin (SN) immunoreactivity (the secretogranin II (SgII) fragment) are similarly present in retinal ganglion cells (RGCs), which is an extrapituitary site of GH expression, and in quail QNR/D cells, which provide an experimental RGC model. The expression of SgII and chromogranin A in the pituitary gland, neuroretina and QNR/D cells was confirmed by RT-PCR analysis. Western blotting also showed that the SN-immunoreactivity in somatotrophs and QNR/D cells was associated with multiple protein bands (24, 35, 48, 72, 78, 93 and 148kDa) of which the 72kDa and 148kDa bands were most abundant. Secretoneurin was constitutively secreted from QNR/D cells as 35kDa and 37kDa proteins and unlike GH, was not increased by exogenous GH-releasing hormone (GHRH). Intracellular analysis by EM showed co-localization of GH and SN in cell bodies and neurites in QNR/D cells. This co-localization was associated with small dark bodies in the neurites. In addition, co-localization of GH and SNAP-25 in the cell surface of QNR/D's plasma membranes suggests GH-release involves specific vesicle-membrane recognition in QNR/D cells. As SN is a marker for secretory granules, GH secretion from RGCs is thus likely to be in secretory granules, as in somatotrophs.

Salivary and serum chromogranin A and α-amylase in periodontal health and disease

BACKGROUND

Salivary stress-related biomarkers in connection with periodontal disease have not been extensively studied. In addition to cortisol as a well-known marker of stress loading, chromogranin A (CgA) and α-amylase (AA) are supposed to link the activity of the neuroendocrine system to local and systemic immune functions and to be related to periodontitis. This study aims to determine CgA and AA in saliva and serum in periodontal health and disease to assess their potential relationship to periodontitis.

METHODS

Patients with aggressive (AgP) (n = 24) and chronic periodontitis (CP) (n = 34) as well as healthy control (CO) (n = 30) individuals participated in this study. CgA and AA were determined in saliva and serum with enzyme-linked immunosorbent assay and an adapted clinical amylase test; salivary cortisol was determined using mass spectrometry. Clinical parameters of periodontal disease were evaluated, and their possible correlations with stress-related biomarkers were assessed.

RESULTS

Significantly higher CgA levels were found in the saliva of patients with AgP compared with those in patients with CP and CO individuals (P <0.001). Salivary cortisol levels were higher in the AgP group compared with those in patients with CP (P <0.05). No differences in serum CgA levels and salivary and serum AA activities were found among all groups. A positive correlation was revealed between salivary AA activity or salivary CgA levels and the extent of periodontitis (P <0.05).

CONCLUSION

The results suggest an association of CgA and cortisol levels as well as AA activity in saliva with periodontitis, especially a significant relationship of salivary CgA and cortisol to AgP.

Chromogranin 'A' in normal subjects, essential hypertensives and adrenalectomized patients

OBJECTIVE

Chromogranin A (CgA) is an acidic glycoprotein co-stored in vesicles and co-released with catecholamines. Although currently used as a humoral marker of endocrine tumours, several aspects of CgA secretion still need to be clarified in humans.

PATIENTS

Fifty-four controls, 83 essential hypertensive and six adrenalectomized patients were studied.

DESIGN

In the controls and hypertensive patients, CgA and catecholamines were measured before (supine position) and after changes in posture (2' upright position), insulin-induced hypoglycaemia (0.15 IU/kg i.v.) and glucagon injection (1 mg i.v.). In addition, blood samples were taken in the morning (0800 h) and in the afternoon (1800 h), and every 5 h for 24 h. In the adrenalectomized patients, blood samples were obtained in the morning and in the afternoon.

MEASUREMENTS

CgA was measured by an immunoradiometric assay, and noradrenaline and adrenaline by high-performance liquid chromatography.

RESULTS

In controls, posture slightly increased plasma catecholamines without affecting CgA levels. Hypoglycaemia evoked a rise in noradrenaline (P < 0.04), adrenaline (P < 0.01) and CgA (79.6 +/- 11.8 vs. 46.1 +/- 10.1 microg/l, P < 0.03). Glucagon injection increased plasma adrenaline (P < 0.01) but not noradrenaline or CgA levels. At variance with blood pressure and catecholamines, CgA increased significantly in the afternoon (51.1 +/- 4.0 vs. 45.0 +/- 3.9 microg/l, P < 0.05); it also had a circadian rhythm, with peak values during the night (at 2300 h, 65.4 +/- 9.0 microg/l) and a nadir in the morning (at 0800 h, 43.1 +/- 6.6 microg/l). In hypertensives, basal and stimulated CgA levels as well as diurnal/circadian variations of this peptide were similar to those in normal subjects. In adrenalectomized patients plasma CgA in the morning (34.3 +/- 6.5 microg/l) was lower (P < 0.03) than in all controls and hypertensives studied, but also showed an afternoon increment (46.4 +/- 6.6 microg/l, P < 0.003). No correlation was found between CgA and catecholamines or blood pressure in all subjects or in the subgroups.

CONCLUSIONS

In normal humans, chromogranin A and catecholamines are not always co-secreted, and co-secretion occurs only for marked exocytotic adrenergic stimuli, such as hypoglycaemic stress. In addition, chromogranin A has a circadian rhythm unrelated to plasma catecholamines. Basal plasma concentrations and the secretory pattern of chromogranin A in hypertensives do not differ from the findings in controls. Finally, the adrenal glands contribute partially to circulating chromogranin A and are not involved in the circadian rhythm of this peptide in humans.

Relative amounts and molecular forms of NESP55 in various bovine tissues

NESP55 (neuroendocrine secretory protein with Mr 55,000) comprises a novel chromogranin-like protein, which is paternally imprinted at the genomic level. We used antisera raised against GAIPIRRH, a peptide present at the C-terminus of this protein, and against TC-14, a peptide located in the N-terminal half of NESP55. Radioimmunoassay, gel-filtration chromatography and immunoblotting were used to determine the levels and the molecular forms of NESP55 in different bovine organs. The tissues with the highest levels of GAIPIRRH immunoreactivity were, in decreasing order: the adrenal medulla, the anterior pituitary, the posterior pituitary, various brain regions, and the intestine. The degree of proteolytic processing revealed differences among the tissues analyzed. The lowest processing was detected in the anterior pituitary and in the brain where only a peak corresponding to the intact precursor was present. This was also true for cerebrospinal fluid (CSF). In the posterior pituitary and in the intestine, the free peptide GAIPIRRH was the predominant molecular form. GAIPIRRH-IR, as in the CSF, is present in serum mainly as an intact precursor. A relatively high concentration of GAIPIRRH-IR was found in the kidney medulla, probably due to an endocytotic re-uptake of this molecule from the tubuli after filtration in the glomeruli. The present study is consistent with the concept that NESP55, like the other chromogranins, becomes proteolytically processed. The function of this new chromogranin-like protein, therefore, might be to represent a precursor of biologically active peptides.

Application of region-specific immunoassay for human chromogranin A: substantial clue for detection and measurement of chromogranin A in human plasma

Chromogranin A (CgA), a secretory protein, is co-released with catecholamines from storage vesicles. It is known to be elevated in the circulation of patients with neuroendocrine and endocrine tumors. For further investigation of the protein, especially in humans, it is essential to facilitate quantitative analysis of the protein in human biological materials. In order to introduce novel immunological methodology for this purpose, we purposely selected human CgA(344-374) for the synthetic immunogen to produce region-specific CgA antibodies. The anti-synthetic peptide antibody thus obtained made it possible to develop an immunological method for measurement and characterization of CgA in human plasma. The plasma CgA-immunoreactivity (LI) level measured by the method was 0.31+/-0.01 pmol/ml (mean+/-SEM) in normal subjects and 1.55+/-0.29 pmol/ml in pheochromocytoma. On gel chromatography and HPLC analysis of the plasma of patients with pheochromocytoma, the region-specific assay system enabled us to show the presence of N-terminal truncated CgA, besides CgA itself. By following up changes of plasma CgA-LI in a pheochromocytoma patient using samples that were collected consecutively over a two-year period, the present assay system using the region-specific antibody, anti-human CgA (344-374) serum, was confirmed to be extremely valuable for the measurement of CgA-LI in human plasma. The characteristic features and high sensitivity of the present assay system will give us a substantial clue to the detection and measurement of CgA to develop further investigation of the protein in humans.

Human pheochromocytoma: different patterns of catecholamines and chromogranins in the intact tumour, urine and serum in clinically unsuspected cases

Clinically unsuspected pheochromocytoma is usually discovered either at autopsy or during surgical intervention for unrelated conditions, despite often enormous neoplastic masses producing and storing catecholamine (CA). In order to assess whether these tumours share some common features we have compiled data for six patients admitted to hospital without previous diagnosis of their pheochromocytoma. The clinical variables and the morphological and immunohistochemical characteristics of the tumours revealed that these cases represented quite different expressions of adrenomedullary neoplasms. They differed not only with respect to nuclear ploidity and overall cytoplasmic morphology but also in catecholamine storage and expression of immunoreactive chromogranin A sequences in the intact tissue. In two of the patients hypertension had been overlooked as a diagnostic indicator of their CA-producing tumours. There was no clear relationship between the mean arterial pressure, the tumour content of CA and the serum levels of CA. Processed chromogranin A dominated in the serum of the two hypertensive cases. The 24-h urine values of CA and its main metabolite (vanillin mandelic acid) were, together with the serum values of chromogranin A and B, proportional to tumour mass and provided the most reliable diagnostic indicators for the non-hypertensive as well as the hypertensive cases.

Sympatho-adrenal secretion in humans: factors governing catecholamine and storage vesicle peptide co-release

1. In postganglionic sympathetic neurones and adrenal chromaffin cells, catecholamines are co-stored in vesicles with soluble peptides, including chromogranin A (CgA) and neuropeptide Y (NPY), which are subject to exocytotic co-release with catecholamines. 2. Plasma catecholamine, CgA and NPY responses to stimulators and inhibitors of sympatho-adrenal catecholamine storage and release were measured in humans. Short-term, high-intensity dynamic exercise, prolonged low-intensity dynamic exercise, and assumption of the upright posture, in decreasing order of potency, predominantly stimulated noradrenaline (NA) release from sympathetic nerve endings. Only high-intensity exercise elevated CgA and NPY, which did not peak until 2 min after exercise cessation. Stimulated NA correlated with plasma CgA 2 min after exercise, and with NPY 5 min after exercise. 3. Insulin-evoked hypoglycaemia and caffeine ingestion, in decreasing order of potency, predominantly stimulated adrenaline (AD) release from the adrenal medulla. During insulin hypoglycaemia AD and CgA rose, but NPY was unchanged. Neither NPY nor CgA were altered by caffeine. The rise in CgA after intense adrenal medullary stimulation was greater than its rise after intense sympathetic neuronal stimulation (1.4-versus 1.2-fold, respectively). 4. Infusion of tyramine, which disrupts sympathetic neuronal vesicular NA storage, elevated systolic blood pressure and NA, while NPY and CgA were unchanged. After reserpine, another disruptor of neuronal NA storage, NA transiently rose and then fell; NPY and CgA were unaltered. After the non-exocytotic adrenal medullary secretory stimulus glucagon. AD rose while NA, CgA and NPY did not change. After amantadine, an inhibitor of protein endocytosis, both CgA and fibrinogen rose, while NA and NPY remained unaltered. Neither CgA, NPY, nor catecholamines were altered by the catecholamine uptake and catabolism inhibitors desipramine, cortisol, and pargyline. 5. Human sympathetic nerve contained a far higher ratio of NPY to catecholamines than human adrenal medulla, while adrenal medulla contained far more CgA than sympathetic nerve. 6. It is concluded that peptides are differentially co-stored with catecholamines, with greater abundance of CgA in the adrenal medulla and NPY in sympathetic nerve. Activation of catecholamine release from either the adrenal medulla or sympathetic nerves, therefore, results in quite different changes in plasma concentrations of the catecholamine storage vesicle peptides CgA and NPY. Only profound, intense stimulation of chromaffin cells or sympathetic axons measurably perturbs plasma CgA or NPY concentration; lesser degrees of stimulation perturb plasma catecholamines only. Neither CgA nor NPY are released during non-exocytotic catecholamine secretion.

Chromogranin A: secretion of processed products from the stimulated retrogradely perfused bovine adrenal gland

Chromogranin A (CGA) is a member of a family of highly acidic proteins co-stored and co-secreted with adrenaline and noradrenaline in the adrenal medulla. A number of biologically active fragments of CGA (CGAFs) have been characterized including a group of small N-terminal fragments collectively named vasostatins due to their vascular inhibitory activity. In the present study, the release of CGAFs, including CGA N-terminal fragments, from the isolated, retrogradely perfused bovine adrenal gland, has been studied under basal conditions and during nerve stimulation and perfusion with acetylcholine. The CGAFs were characterized by SDS-PAGE followed by immunoblotting with antisera to specific sequences within the CGA molecule. Many different CGAFs were released during stimulation of the glands. Antisera to CGA1-40 and CGA44-76 detected a 7 kD protein whose release was increased during stimulation. This component co-migrated with synthetic CGA1-76, was not immunoreactive to antisera to CGA79-113 or CGA124-143, and was seen whether or not the serine protease inhibitor aprotinin was present in the perfusion medium. The release of an approximately 18 kD component, which stained with antisera to CGA1-40, CGA44-76 and CGA79-113, but not to chromostatin (CGA124-143), was also increased during stimulation. Components of 22 kD and larger were detected with antisera to chromostatin, but not with antisera to CGA1-40, CGA44-76 and CGA79-113. Two of these components of 22 to 24 kD were enhanced during nerve stimulation in the presence of aprotinin. The results indicate that processed chromogranin A fragments are secreted from the bovine adrenal medulla during stimulation of chromaffin cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasostatins, comprising the N-terminal domain of chromogranin A, suppress tension in isolated human blood vessel segments

Chromogranin A (CGA) belongs to a family of highly acidic proteins which are co-stored and co-released with the catecholamines from the mammalian adrenal gland and occur in nmolar concentrations in the human circulation. A vascular function for the adrenomedullary released and circulating CGA has yet to be established. The present study reports on the novel vasoinhibitory effect of the N-terminal domain of the adrenomedullary CGA in isolated segments of the human internal thoracic artery (ITA) and saphenous vein (SV). The collective term vasostatin(s) refers to N-terminal fragments (CGA1-76 and CGA1-113) of apparent molecular weights 7 to 22 kD, to indicate their vascular inhibitory effects. The sustained contractions evoked by the potent vasoconstrictor peptide, endothelin-1 (ET-1) were suppressed when ITA and SV segments were preincubated for 15 min with vasostatins (72 nM). The vasoinhibitory effects were not dependent on an intact endothelium and suppression of the response to 35 nM ET-1 was approximately 77% and approximately 40% in endothelium-denuded ITA and SV segments, respectively. In endothelium-denuded SV segments the vasostatins suppressed the maximal sustained tension response but not the potency for ET-1, indicating that the vasostatin effect did not involve interference with ET-1 binding to its vascular receptor. Preincubation of endothelium-denuded SV segments with nifedipine (1 microM) inhibited the sustained response to ET-1 > or = 10 nM by 50%.(ABSTRACT TRUNCATED AT 250 WORDS)

Posttranslational processing of proenkephalins and chromogranins/secretogranins

Posttranslational processing of peptide-precursors is nowadays believed to play an important role in the functioning of neurons and endocrine cells. Both proenkephalins and chromogranins/secretogranins are considered as precursor molecules in these tissues, resulting in posttranslationally formed degradation products with potential biological activities. Among the proteins and peptides of neuronal and endocrine secretory granules, the enkephalins and enkephalin-containing peptides have been most extensively studied. The characterization of the post-translationally formed degradation products of the proenkephalins have enabled the understanding of their processing pathway. Chromogranins/secretogranins represent a group of acidic glycoproteins, contained within hormone storage granules. The biochemistry, biogenesis and molecular properties of these proteins have already been studied for 25 years. The chromogranins/secretogranins have a widespread distribution throughout the neuroendocrine system, the adrenal medullary chromaffin granules being the major source of these storage components. Recent data provide evidence for a precursor role for all members of the chromogranins/secretogranins family although also several other functions have been proposed. In this review, some of the methods applied to study proteolytic processing are described. In addition, the posttranslational processing of chromogranins/secretogranins and proenkephalins, especially the biochemical aspects, will be discussed and compared. Recent exciting developments on the generation and identification of potential physiologically active fragments will be covered.